Modified 9.8hp outboard

After a long list of modifications the 9.8hp is starting to really scream.
I am very impressed, especially with the torque and speed pickup compared to a stock 9.8hp.
Subscribe as there is more videos coming on this.
Also check out my modified 5hp videos, so much fun 🤩

[@thomasmartenson4862]

Best channel ever. Internet is full of jack asses that want to comment on everything but in reality they're just the opposite of this gut. Definetly right attitude.❤

[@25hpboatracerman]

Mate, that’s so so nice 😊 Thanks for your encouragement champion. Hope you can get out on the water and enjoy yourself soon. All the best, Aussie Boat Guy 😎

[@josephhalwagy6435]

You are a legen. Always great watching your clips.

[@25hpboatracerman]

Thanks champion 👌 Love your encouragement. All the best, Aussie Boat Guy 😎

[@nativehuman6841]

I’ve been waiting for this video love your work I already have to many questions

[@25hpboatracerman]

😂😂 I’ve been waiting too 😁 Been too busy to test the mod 9.8 unfortunately. Yesterday was the day, so much fun. More vids coming and I will show what I’ve done. Cheers 🍻 Aussie Boat Guy 😎

[@femountain]

Wow, two stroke rules😎

[@25hpboatracerman]

Yes, yes they do 😁😁 I’m a massive fan of two strokes. Cheers 🍻 Aussie Boat Guy 😎

[@bradleyfarquhar2023]

good stuff mate what a huge difference a lot more power.

[@25hpboatracerman]

Hi mate, Yeah, I’m so happy with it 😁😁 Next I need to make a low water pickup gearcase with nose cone and a special skeg. All the best, Aussie Boat Guy 😎

[@jimstaines8093]

I’ve looked at all of these 9.8 modification videos of yours, what a great step by step guide. Keen to talk to you further about what’s possible on a 2001 USA 9.9 Merc

[@25hpboatracerman]

Cheers mate. Appreciate your comments. Thanks 😊 Aussie Boat Guy 😎

[@michaelsimpson9779]

Nice, always be good to improve efficiency and get the best out of something. 👍

[@25hpboatracerman]

Thanks mate 😊 I fully agree and I was keen to do it to this outboard as it’s incredibly light as well. All the best, Aussie Boat Guy 😎

[@user-hk8kw6hl1s]

Killer! Love it!!

[@DatBlueHusky]

ripping! i want to see you add expansion pipes to one of these motors and have it exit out the bottom to make it quiet while having more power

[@25hpboatracerman]

Hi champ, You think the same as me 😁 Been thinking that for a while but at this stage I’m just trying to see what I can get out of a stock looking motor. I’m sure the pipes will come in the future 😂😂 Cheers 🍻 Aussie Boat Guy 😎

[@Fwdking]

9.8 Tohatsu are a great motor.

[@25hpboatracerman]

Yep, one of my favorite 🤩 cheers 🍻 Aussie Boat Guy 😎

[@glockeva1]

Well done, that outboard fly's!. I had a 2006 9.8 long shaft, I wish I never sold it because it was light and powerful. Great video

[@25hpboatracerman]

Thanks mate, yeah I’m so happy with it. I’ve owned about 5 9.8hp outboards over the years and glad I have finally modified one. You can always search for another one, they are great being so light for the power they put out. Cheers 🍻 Aussie Boat Guy 😎

[@glockeva1]

@@25hpboatracerman I might just do that... I had my 9.8 on a 11ft dory and it pushed it along nicely, I can imagine it would absolutely fly with your 18 hp carb set up 👍

[@25hpboatracerman]

@@glockeva1 Yeah, it would. Top end speed is a bit more but the power onto the plane and mid range punch is incredible Cheers 🍻 Aussie Boat Guy 😎

[@aarondavis9044]

Just buy the 18hp only 41kgs 👍

[@25hpboatracerman]

@@aarondavis9044 True, love the 18hp. But if you need to carry your outboard (as I often do down to the water at about 300m) then the 26kgs is way better and now it gps speed clocked at 50kph so it’s nearly on par with the top end speed of the 18 👌 Ps: I’m sure I will end up modding an 18hp too. Cheers 🍻 Aussie Boat Guy 😎

[@phillipsemmens1786]

Gday there. I have modified carb on a 5hp parson 4stroke. Used to do nothing 2thirds throttle and above. After finding webber carb calculations i have bored venturi out 2mm to match throttle bore and port matched carb and manifold. Recorded all before and after mods of air jets and fuel jet sizes. Am lean on main jet so made air bleed smaller. About to test it. Carb been on and off plenty times playing with fuel and gets better each time

[@25hpboatracerman]

Hi mate, Good work, and sounds like your having as much fun as me, keep it up 👍 Cheers 🍻 Aussie Boat Guy 😎

[@DktheWelder]

Cool! Would like to see some more details, do you have a different prop on it?

[@25hpboatracerman]

Hi mate, Hope to be giving more details on mods in a future vid. It’s just running the standard alloy prop and standard gearcase in that video. I’m just trying to get the jetting off the bigger carb right, still not quite there 🤦‍♂️🤦‍♂️ I tried the 5hp race prop on that motor but running full depth. It hit 50kph gps but it’s not enough prop for it. Got a few props I want to try once I raise the motor 😁😁 Cheers 🍻 Aussie Boat Guy 😎

[@72mardy]

Would love to see how that engine would go on my 10' Quintrex punt 😋

[@25hpboatracerman]

Hi mate, Probably go about the same as my test boat which is a 8ft tinny. Cheers 🍻 Aussie Boat Guy 😎

[@onemantwohands5224]

Gidday mate! Have you considered flat slide carb fir this engine ? Im building the same engine to basically your specs, proper porting and the half mil shave yuve done 👍. Im excited! Could you please let me know the jetting in the 18 carby , ill definitely start there if youd be so kind ! Cheers buddy love these videos ❤

[@25hpboatracerman]

That’s awesome mate, Did you make a new exhaust tuner and do the reed plate mods too? I used the 22mm throat 18hp carb (there is a 20mm throat too) I have ended up with a .60 low jet and I had to modify the main and reduce it to 1.02 as the 1.1mm was flooding the motor, still playing with the jets as it’s still not perfect. So the 18hp 22mm throat carb normally has a .60 low and a 1.16 main jet. The 20mm throat carb normally has a .80 low jet and a 1.1 main. Just for your info. Please keep me posted on your progress. I’ve got a lower uni build video coming for that motor too

[@nerd1000ify]

Ducks guts Max! Wonder how much power you're making now?

[@25hpboatracerman]

Hi mate, Thanks, I’m loving it. I don’t really know how much power all I know is it’s more than it was 😁 Guessing 13 or 14hp

[@rrrttt1112]

This is awesome! Been waiting for you to work on one of these beasts! So, you said the motor is built to run rpms over 7000, is that the specs, or what your specs are after you did all the mods? Thanks (great job, am looking forward to more about this 9.8!)

[@25hpboatracerman]

Hi mate, Thanks for your comments 😊 Yeah, I changed the port timing so that the power will still be available at higher rpm. I built a custom exhaust tuner with a different shape and bigger internal than standard, it has 15psi more compression than stock, massive modifications to the intake and reeds, plus porting and the 18hp carburetor which has a 22mm throat instead of the standard 17mm throat. Still fine tuning the jetting in the bigger carburetor. Cheers 🍻 Aussie Boat Guy 😎

[@Phantom-mk4kp]

​@@25hpboatracermanIs the 15 PSI increase in compression measured before or after you changed the port timing?

[@25hpboatracerman]

@@Phantom-mk4kp Very good question 👍👌 Looks like you know that I raised the exhaust ports 😁 Yep, the 15psi increase is after the port timing change and measured after motor is all back together. I would have gone more if I could but more than that I would have to add material to the combustion chambers, maybe in the future. Cheers 🍻 Aussie Boat Guy 😎

[@Phantom-mk4kp]

@@25hpboatracerman looking forward to the full tech videos on this. What was limiting more head skimming? Cutting into the water jacket?

[@25hpboatracerman]

@@Phantom-mk4kp Hi mate, It was the standard squish bands that are the limiting factor to how much I could skim off the head. I could shave more and then re-turn the squish bands but just want to see what it can achieve with that head as shaving was pretty easy, gaining more comp than what I’ve got will be a big effort. Cheers 🍻 Aussie Boat Guy 😎

[@FYMM69]

Have you experimented at all with dumping exhaust above waterline ??

[@25hpboatracerman]

Hi Champion, Sure have, check out some of the later vids on that motor, I made a low water pickup gearcase with above cav plate exhaust, so awesome 👏 Cheers 🍻 Aussie Boat Guy 😎

[@richo4625]

Hey Mate, would you ever use a aftermarket crankshaft in a 9.9 or always go OEM?

[@25hpboatracerman]

Hi Mate, I wouldn’t normally but I am actually considering it because of the costs. Cheers 🍻 Aussie Boat Guy 😎

[@stefanhellemar4501]

👍🏿

[@acs108]

I thought it was only the 9.9 with the 18 block that you could do this to.

[@25hpboatracerman]

Hi mate, Any outboard can be modified 👌 The 9.9hp Tohatsu can be modified with bolt on parts from the 18hp but it only shares the same block as the 15hp, the 18hp looks the same but has more capacity and way bigger ports from factory. My 9.8hp shares the same block as the 6hp and 8hp so all my mods I have to make or do myself. Cheers 🍻 Aussie Boat Guy 😎

[@acs108]

@@25hpboatracerman awesome stuff mate. So what parts would I be able to bolt on to the 9.9?

[@LightSkinCapabilities]

Does that mean that the 12hp hangkai is the same as the 15hp tohatsu since the hangkai 12hp matches the 9.9hp tohatsu? Do you go by model numbers?

[@pauloconnor7951]

And an expansion chamber will give another 25% approx. It'll feel like double the power.

[@25hpboatracerman]

Hi mate 👋 Yeah I agree, would love an expansion chamber but unfortunately as soon as I put a chamber on I will get in trouble for noise pollution here. Cheers 🍻 Aussie Boat Guy 😎